Vehicular camera and lens assembly and method of manufacturing same

ABSTRACT

A method of assembling a vehicular camera includes providing a lens assembly having a base portion, a lens barrel and a plurality of optical elements in the lens barrel, and providing a circuit element having a circuit board and an imaging array. An adhesive bead is dispensed at the base portion and/or circuit element. The circuit element is placed at the base portion with the adhesive bead therebetween and the optical elements are aligned with the imaging array via a six axis robotic device when the circuit element is at the base portion and in contact with the adhesive bead. The adhesive bead is cured to a first cure level via exposure of the adhesive bead to ultraviolet light. The assembly is moved to a second curing stage and the adhesive bead is cured to a second cure level via heating the adhesive bead.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a 371 national phase filing of PCTApplication No. PCT/US2012/061548, filed Oct. 24, 2012, which claims thefiling benefit of U.S. provisional application, Ser. No. 61/550,664,filed Oct. 24, 2011, which is hereby incorporated herein by reference inits entirety, and the present application is a continuation-in-part ofU.S. patent application Ser. No. 14/033,964, filed Sep. 23, 2013, whichis a continuation of U.S. patent application Ser. No. 13/260,400, filedSep. 26, 2011, now U.S. Pat. No. 8,542,451, which is a 371 nationalphase filing of PCT Application No. PCT/US2010/028621, filed Mar. 25,2010, which claims the benefit of U.S. provisional applications Ser. No.61/232,544, filed Aug. 10, 2009, and Ser. No. 61/163,240, filed Mar. 25,2009.

FIELD OF THE INVENTION

The invention relates to vehicular cameras, and more particularly, tolow cost construction and assembly of such cameras.

BACKGROUND OF THE INVENTION

Vehicular cameras are used for a variety of purposes, such as to assista driver in avoiding obstacles behind a vehicle when backing up, and todetect imminent collisions ahead of the vehicle when driving forward. Avehicular camera includes a lens that focuses video input on an imagesensor provided on an imager. In general, the position of the lensrelative to the image sensor can impact the quality of the video inputreceived by the image sensor. For example, if the lens is positionedsuch that the video input is not in focus, then the video informationpassed to the driver may be blurry, and other vehicular systems, such asa collision detection system for example, may not function as well asthey otherwise could. As the size of the camera is reduced, thepositioning of the lens relative to the image sensor may be relativelymore critical, at least because small variations in position can resultin relatively large changes in angular offset. Therefore, thepositioning of the lens relative to the image sensor may be particularlycritical for vehicular rearview cameras. Furthermore, it is importantthat the camera be capable of holding the lens in position over aselected period of time under certain operating conditions, so that theperformance of the camera is maintained over a useful operating life.

Several aspects of the camera may contribute to the overall tolerance inthe position of the lens relative to the image sensor. For example, forlenses and lens holders that are threaded, the threaded connectiontherebetween has a tolerance associated with it. The angle of cast ofthe lens holder has a tolerance associated with it. The position of theimager has a tolerance associated with it.

It is desirable to provide a more integrated, lower cost camera assemblywith means for positioning the lens relative to the imager withintolerance.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to a vehicular camera having alens that is mounted to a lens holder and is held in position by aselected adhesive. The adhesive is capable of being initially curedrelatively quickly by exposure to UV light for supporting the lensrelative to the lens holder. The adhesive is further capable of beingcured by exposure to a secondary curing condition, such as by exposureto heat, to achieve a fully cured strength, which may take a relativelylonger period of time, such as minutes or hours.

By providing an adhesive that is initially curable quickly but thatreaches a selected fully cured strength and selected performancecharacteristics, the camera lends itself to having the lens and/orimager circuit element or printed circuit board (PCB) positioned by arobot or a multi-axis motion system and then having the adhesive curedquickly to fix the relative position of the lens and the imager PCB sothat the camera can be transferred from the robot or the multi-axismotion system to a second curing fixture for exposure to the secondarycuring condition to fully cure the adhesive. Thus, the robot or themulti-axis motion system, which may be a relatively expensive componentof a system used to manufacture the camera, can be used to align thelens or imager PCB and hold the assembly for a short period of timeduring the initial curing stage, and then the partially cured assemblymay be moved to the secondary curing station and the robot or themulti-axis motion system may be used to adjust and align the lens ofanother camera while the first camera is being fully cured. The robot ormulti-axis system is operable to grab and move objects in up to sixdegrees of motion or six axes of motion: translational movement in threegenerally orthogonal translational axes (in the x, y and z directions)and rotational movement about three generally orthogonal rotational axes(commonly referred to as pitch, yaw and roll). In the embodimentsdescribed below, some require all six axes of motion while some requireonly five axes of motion (such as motion in the x, y and z direction,and pitch and yaw rotational motion), or even less number of axes ofmotion, depending on the application requirements. For the simplicityreason, we will refer to all multi-axis motion systems herein as“robots” or “robotic devices”. The robot of the present inventionprovides for roll or rotation about the optical axis of the lens or lensassembly in addition to the translational movement in the x, y and zdirections and in addition to the pitch and yaw motions, thus providingenhanced and more precise and accurate placement and alignment of thelens at the imager circuit element or printed circuit board.

According to an aspect of the present invention, a method of assemblinga vehicular camera includes providing a lens assembly comprising a baseportion, a lens barrel and a plurality of optical elements in the lensbarrel. A circuit element is provided that comprises a circuit board andan imaging array established at the circuit board. At least one adhesivebead is dispensed at the base portion of the lens assembly and/or at thecircuit element. The circuit element is placed at base portion of thelens assembly with the at least one adhesive bead between the circuitelement and the base portion, and the optical elements are aligned withthe imaging array when the circuit element is placed at the base portionand in contact with the adhesive bead. The at least one adhesive bead iscured to a first cure level via exposure of the at least one adhesivebead to ultraviolet light. The at least one adhesive bead is furthercured to a further cure level via a further exposure of the at least oneadhesive bead to ultraviolet light. The lens assembly and the circuitelement are moved to a second curing stage and the at least one adhesivebead is cured to a second cure level via heating the at least oneadhesive bead to an elevated temperature for a selected period of time.A housing portion is attached to the base portion of the lens assemblyto encase the circuit element and to substantially seal the housingportion and the base portion together.

The adhesive may comprise any suitable adhesive, such as an adhesivethat may be partially cured via exposure to ultraviolet (UV) light andfully cured via exposure to heat, such as, for example, adhesive AD VE43812 by Delo Industrial Adhesives of Windach, Germany, such asdescribed in U.S. patent application Ser. No. 13/260,400, filed Sep. 26,2011, now U.S. Pat. No. 8,542,451, and PCT Application No.PCT/US2010/028621, filed Mar. 25, 2010 and published Sep. 30, 2010 asInternational Publication No. WO 2010/111465, which are herebyincorporated herein by reference in their entireties.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only withreference to the attached drawings in which:

FIG. 1 is an exploded perspective view of a vehicular camera inaccordance with an first embodiment of the invention wherein a lensbarrel is adhesively secured to a lens holder via a UV-curable adhesive;

FIG. 2 is a cutaway side view of the vehicular camera shown in FIG. 1,in an assembled state;

FIG. 3 is a schematic cross-sectional view of a variant of the firstembodiment;

FIG. 4 is a cross-sectional view of a prior art lens;

FIG. 5 is a schematic cross-sectional view of a second embodiment of theinvention wherein a lens barrel is integrated with a camera lens holder;

FIG. 6 is a schematic cross-sectional view of a third embodiment of theinvention wherein a lens barrel is dropped on a surface of an imager;

FIG. 6A is a detail view of a portion of FIG. 6;

FIG. 7 is a schematic cross-sectional view of a variant of the thirdembodiment;

FIG. 8 is a detail cross-sectional view of the third embodiment;

FIG. 9 a schematic cross-sectional view of a fourth embodiment of theinvention wherein a lens is focused by PCB mounting screws;

FIG. 10 is a schematic cross-sectional view of the fourth embodimentincluding a back housing;

FIG. 11 is a schematic cross-sectional view of a fifth embodiment of theinvention wherein a lens is focused by the selective positioning ofcamera front and back housings;

FIG. 12 is a schematic cross-sectional view of a variant of the fifthembodiment;

FIG. 13 is a schematic cross-sectional view of a variant of the fifthembodiment, wherein a PCB is selectively positioned;

FIG. 14 is a schematic cross-sectional view of a sixth embodiment of theinvention wherein a lens is focused by directly attaching a lens to animager through a transparent adhesive;

FIG. 15 is a graph of a contrast sensitivity function;

FIG. 16 is a graph of an example of lens chromatic aberration;

FIG. 17 is an exploded perspective view of a camera assembly inaccordance with the present invention;

FIG. 18 is another exploded perspective view of the camera assembly ofFIG. 17;

FIG. 19 is an exploded perspective view of another camera assembly ofthe present invention;

FIG. 20 is a block diagram of the assembly process for assembling thecamera assembly of FIGS. 17 and 18;

FIG. 21 is another block diagram of the assembly process for assemblingthe camera assembly of FIGS. 17 and 18; and

FIG. 22 is a block diagram of the assembly process for assembling thecamera assembly of FIG. 19.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and the illustrative embodiments depictedtherein, a camera is assembled with a circuit board or element (such asa printed circuit board comprising a semiconductor substrate andcircuitry established thereon and having an imaging array disposed orestablished thereat) adhered to a lens assembly so that the lens opticsof the lens assembly are precisely aligned with the imaging array of thecircuit element. The present invention provides for a two stage curingprocess that includes an initial or first or partial curing of theadhesive when the lens optics are aligned with the imaging array andmechanically held in place, such as via a robot or the like, and then asecond or subsequent or full curing of the partially cured adhesive at aseparate curing station so that the robot, which functions to hold andplace and align the imaging array and lens optics, can be used forassembling other cameras while the first camera is being fully cured(which can take several minutes in a heat chamber or the like).

Conventionally, a three, four or five axis movable stage (that providesfor movement in the x, y and z directions and may provide for pitchand/or yaw adjustment or motion) has been used for the placement andgluing of a lens or lens assembly to an imager surface or circuitelement. Such a five axis adjustment has the disadvantage of not beingable to achieve a roll motion or rotation (along the optical axis) ofthe imager or lens during the placement and gluing process. For example,if the imager is not properly aligned and oriented relative to thecamera body, when the camera is later mounted at a vehicle at theselected or appropriate orientation relative to the vehicle mountingstructure, the imager may not be aligned or oriented properly withrespect to the vehicle, such that the images captured by the imager maybe skewed or otherwise not suitable for viewing and discerning by thedriver of the vehicle.

We have found that use of a six axis robot or six axis stage, whichincludes roll capability or rotation about the optical axis (in additionto translational motion in the x, y and z directions and pitch and yawrotational motion), overcomes the disadvantages of known movable stagesand provides for enhanced alignment and positioning of the lens opticsand imager relative to the camera body. For example, the robot andmethod of the present invention provides three generally orthogonal axesof rotation (pitch, yaw and roll) of a head and three generallyorthogonal axes of translation (in the x, y and z directions) of thehead to provide enhanced or more accurate alignment and/or placementand/or movement of the lens and imager circuit element assembly to thecamera body during the placement and gluing process. As a result of thisadjustment and alignment capability, the rotational tolerances of theimager relative to the camera body can be corrected or minimized.

The present invention may provide for adhering the circuit board to abase portion of a lens assembly, such as by holding the lens assembly ina fixture and using a robot to position and align and place the circuitboard at the lens assembly and at the adhesive bead or beads or dotsdispensed at the base portion of the lens assembly, and to align theimaging array with the lens optics, such as discussed below with respectto FIGS. 17-22. Optionally, the present invention may provide foradhering a lens barrel (with lens optics therein) to a barrel receivingportion of the camera (and attached to a circuit board or element withan imaging array established thereat), with a robot adjusting oraligning the lens barrel and optics relative to the circuit board andimaging array, such as discussed below with respect to FIGS. 1-16, andsuch as by utilizing aspects of the cameras and systems and methodsdescribed in U.S. patent application Ser. No. 13/260,400, filed Sep. 26,2011, now U.S. Pat. No. 8,542,451, which is a 371 national phaseapplication of PCT Application No. PCT/US2010/028621, filed Mar. 25,2010 and published Sep. 30, 2010 as International Publication No. WO2010/111465, which claims the benefits of U.S. provisional applications,Ser. No. 61/163,240, filed Mar. 25, 2009, and Ser. No. 61/232,544, filedAug. 10, 2009, which are all hereby incorporated herein by reference intheir entireties.

Embodiment 1 Use of UV-Curable Adhesive to Mount Lens to Holder

FIG. 1 shows an exploded view of a vehicular camera 10 in accordancewith a first embodiment of the invention. The vehicular camera 10includes an imager 20, a lens holder such as a front camera housing 14and a lens 16. The vehicular camera 10 may include other components suchas additional circuitry for processing the video input received by theimager 20, e.g., circuitry for providing graphic overlay to the videoinput. The vehicular camera 10 may further be configured to transmit thevideo input to other vehicular devices, such as a display controller(not shown) for a cabin-mounted display (also not shown).

The imager 20 may be a charge-coupled device (CCD) or a complementarymetal-oxide semiconductor (CMOS) sensor. Referring additionally to FIG.2, the imager 20 is mounted to a printed circuit board (PCB) 12. Theimager 20 is positioned to receive optical images from the lens 16. Inthe exemplary embodiment shown in FIG. 1, the imager 20 is connected tothe lens holder 14 by a plurality of threaded fasteners 22.

The lens 16 is mounted to the lens holder/front camera housing 14 at aselected position for focusing video input onto the sensing surface ofthe imager 20. The lens 16 may be any suitable type of lens known in theart. The lens 16 may have an exterior surface 24 that is configured tobe received in a cylindrical aperture 26 having an aperture wall 28 onthe lens holder/front camera housing 14. The exterior surface 24 and theaperture wall 28 may have a selected amount of clearance therebetween,shown by a gap G. An adhesive 30 is provided for holding the lens 12 ina specific position relative to the lens holder/front camera housing 14.More particularly, the adhesive 30 may be applied between a first axialface 32 on the lens holder/front camera housing 14, and a second axialface 34 on the lens 16.

The position of the lens 16 relative to the imager 20 impacts the degreeof focus present in the optical images received by the imager 20 andthus the performance of the camera 10 and the optical alignment of theoptical image on the imager.

To control the position of the lens 16 relative to the imager, apositioning system may be provided that includes a robot, such as a fiveaxis robot or a six axis robot as discussed above. Such a robot isoperable to grab and move objects (such as the lens or lens assembly orthe imager and imager circuit board) in up to six axes of motion, suchas along three generally orthogonal translational axes, such as alongeither of the x and y axes or directions (the axes generally parallel tothe plane of the imager and generally orthogonal to the optical axis ofthe lens or lens assembly) and along the z-axis or direction (the axisthat is generally orthogonal to the plane of the imager and generallyalong the optical axis of the lens or lens assembly). In addition to thetranslational movement capabilities of the robot, the robot is alsooperable to move or rotate or pivot the object and the grasping orholding portion or head of the robot about at least two axes andoptionally three axes, so as to provide a pitch rotation or movement(rotation of the held object about one of the generally orthogonal axesgenerally parallel to the plane of the imager and generally orthogonalto the optical axis of the lens or lens assembly) and a yaw rotation ormovement (rotation of the held object about the other of the generallyorthogonal axes generally parallel to the plane of the imager andgenerally orthogonal to the optical axis of the lens or lens assembly),and optionally a roll rotation or movement (rotation of the held objectabout the axis generally orthogonal to the plane of the imager andgenerally along the optical axis of the lens or lens assembly). Therobot holds and adjusts the position of the lens 16 relative to the lensholder/front camera housing 14 until a target object appears in suitablefocus and at a suitable position on the imager 20, prior to hardening ofthe adhesive 30. The adjustment of the lens 16 relative to the lensholder/front camera housing 14 is facilitated by providing the selectedamount of clearance between the exterior surface 24 of the lens 16 andthe aperture wall 28 of the lens holder/front camera housing 14.Additionally, the thickness of the layer of adhesive 30 between the lens16 and lens holder/front camera housing 14 may be selected to provide asuitable amount of relative angular adjustment between the lens 16 andlens holder/front camera housing 14. The thickness of the layer ofadhesive may be approximately 0.75 mm prior to adjustment of the lens16.

Once the lens 16 has been suitably positioned by the robot, the adhesive30 is initially cured by exposure to UV light while the robot holds thelens 16 in position. The UV light may be provided from a plurality of UVsources about the periphery of the camera 10. The initial curing of theadhesive 30 may result in the adhesive being strong enough to hold thelens 16 in the lens holder/front camera housing 14 without needing therobot to grip the lens 16, and may take less than about 7 seconds.However, the lens 16 may be susceptible to movement if it incurs arelatively small disturbance at this stage. After the initial curing,the camera 10 may be placed by the robot relatively gently on a conveyor(not shown) and moved to a UV curing station for a further UV curingperiod, such as, for example, about 25 seconds. Another UV curingstation may optionally be provided to further cure the adhesive 30 foranother period, such as about 25 seconds, after the camera 10 leaves thefirst UV curing station. Subsequent to the UV curing, the camera 10 maybe transferred to another curing station where the adhesive 30 can bethermally cured, or may be cured by exposure to some other secondarycuring condition, to achieve its fully cured strength so that it canhold the lens 16 in position during use on a vehicle. The step ofinitially curing the adhesive 30 using UV light may be relativelyinstantaneous. This step of thermally curing the adhesive may takeseveral minutes or hours. As an additional or alternative curingmeasure, the adhesive 30 may be moisture cured.

Providing an adhesive 30 that has an initial curability by UV light isadvantageous in that the robot is not needed to hold the lens 16 inposition over the period of time that it would take for the secondarycuring condition to sufficiently harden the adhesive 30 to beself-supporting. Once the camera 10 is transferred from the robot to thecuring fixture, the robot can be used for the positioning of anotherlens 16 in another lens holder 14/front camera housing. Because the taskof positioning the lens 16 and initially curing the adhesive 30 using UVlight can take less time than fully thermally curing of the adhesive 30,a single robot can feed cameras 10 with initially cured lenses to aplurality of curing fixtures, thereby providing the capability ofachieving a relatively high rate of production per robot.

Once fully cured, the adhesive 30 may be capable of holding the lens 16in position with at least a selected strength of bond between the lens16 and lens holder/front camera housing 14 under one or more selectedoperating conditions. For example, the adhesive 30 may be capable ofholding the lens 16 in position after a selected time period of 1000hours of exposure to a selected temperature of 85 degrees Celsius andoptionally a humidity of approximately 85 percent. Any of theaforementioned selected values may be selected to suit the particularenvironment that the camera 10 is expected to experience during use. Theselected time period may, for example, be some other time period, suchas approximately 1200 hours. The selected adhesive 30 may be furthercapable of holding the lens 16 in position after a selected time periodexposed to a selected temperature of −40 degrees Celsius. The fullycured adhesive 30 may have other performance characteristics including:maintaining at least 70 percent of its strength (e.g. tensile strength)during exposure to temperatures ranging from −40 degrees Celsius to 95degrees Celsius, having a tensile strength of at least 1000 psi, havinga Shore D hardness value of at least 50, having a viscosity of betweenabout 30000 and 70000 centipoise, being non-hygroscopic (so that it doesnot swell significantly when exposed to moisture), having a cure depthof at least 3 mm, having the capability to bond to PolybutyleneTerephtalate/Polycarbonate and/or Polyphenylene Sulfide and/or liquidcrystal polymer and/or anodized aluminum, having a bond shear strengthof at least 1000 psi with less than a 60 percent reduction in its bondshear strength at 85 degrees Celsius, little or no outgassing, beingcapable of withstanding exposure to salt fog, being capable ofwithstanding typical automotive chemicals, such as gasoline andautomotive cleaning agents, having a glass transition temperature thatis at least 90 degrees Celsius and being ‘automotive-grade’ (i.e. beinggenerally applicable for use in a vehicle).

The adhesive 30 may be applied by the robot itself prior to adjustmentof the lens 16 relative to the lens holder/front camera housing 14.Alternatively, the adhesive 30 may be applied by some other device priorto (or during) possession of the camera 10 by the robot.

Aside from fixing the position of the lens 16 relative to the lensholder/front camera housing 14, the adhesive 30 may also hermeticallyseal the interior of the camera 10 against the outside environment.

Numerous adhesives were attempted for use as the adhesive 30. Forexample, it was found that some adhesives, such as some UV-cure freeradical acrylates that have the capability of being initially curedusing UV light, have a reduced strength (e.g. tensile strength) underexposure to elevated operating temperatures such as about 85 degreesCelsius over a selected period of time. It was further found thatadhesives, such as some UV-curable free radical epoxy hybrids also havea reduced strength (e.g. tensile strength) under exposure to elevatedoperating temperatures such as about 85 degrees Celsius over a selectedperiod of time. Some cationic epoxies that were tried also lost theirstrength when exposed to a temperature of about 85 degrees Celsius and ahumidity of about 85 percent over a selected period of time. Someanionic cyanoacrylates that were tried were unsuitable as they producedtoo much outgas for optical use. Other adhesives, such as some UV-curefree radical silicones have a relatively low dimensional stability andare thus not suitable.

Surprisingly, it was found that a suitable adhesive that can be used forthe adhesive is adhesive AD VE 43812 manufactured by Delo IndustrialAdhesives of Windach, Germany. This adhesive is a low-temperature cure,epoxy-amine adhesive that can be cured initially relatively quickly byexposure UV light.

FIG. 3 shows a variant 100 of the rear view camera 10. This embodimentincorporates a lens 112, a front housing/lens holder 130, a back housing132 and an imager 140. As shown in greater detail in FIG. 4, the lens112 includes a lens barrel 114 in which lens optical elements 120,O-ring 122, spacers 124 and IR cutoff filter 126 are mounted and held inplace by a retainer cap 116. The front housing 130 holds the lens barrel114 via a threaded connection, or an adhesive flange as discussed above.A printed circuit board (PCB) 138 with imager 140 is mounted in thehousing defined by the front and back housing parts 130, 132. Screws 134are used for this purpose. In order to mount the lens 112, it is firstpositioned in the housing 130, 132 by a robot or multi-axis focusingmachine (which may provide six axes of motion or adjustment) so as toprovide a focused image relative to the imager 140 and once properlyaligned the lens 112 is thereafter fixedly attached to the front housing130. The sealing between the lens 112 and front housing 130 ispreferably provided by the adhesive discussed above, or by utilizing athread lock device. Then, the back housing 132 is attached to the fronthousing 130 by laser or ultrasonic welding, adhesive, or via a pressfitting.

Embodiment 2 Integration of Lens Barrel and Camera Lens Holder

FIG. 5 shows another embodiment 110 of a vehicular camera, wherein thelens barrel 114 housing the optical components of the lens 112 and thecamera front housing 130 form a single integrated piece 150. The lensoptical elements 120, O-rings and spacers 122, 124 and IR cutoff filter126 (FIG. 4) are placed inside a lens barrel portion 114′ of theintegrated lens barrel and camera upper housing piece 150 as part of theconventional lens assembly process to provide a lens 112′ (FIG. 5). Theintegrated piece 150 can be formed by plastic injection molding or metalmachining. Plastic injection molding is preferred for lower cost andease of attaching the back housing 132 to the integrated piece 150 bygluing, laser or ultrasonic welding.

The printed circuit board or PCB 138 with imager 140 is mounted to theintegrated piece 110. Lens 112′ is focused relative to the imager 140such as by applying techniques described below with respect toembodiments 3 to 6.

The advantages of this embodiment 110 include a savings in tooling costas one expensive upper housing plastic molding tool is eliminated;material cost savings since less plastic material is used and noexpensive adhesive or thread lock epoxy is needed; and a more simplifiedcamera assembly process since the step of attaching the lens to theupper housing is eliminated.

Embodiment 3 Lens Barrel Dropped on Surface of Imager

FIG. 6 shows another embodiment 200 of a vehicular camera wherein thelens barrel 114′ of the integrated piece 150 is dropped onto and sitsdirectly on top of the surface of the imager 140. During the cameraassembly process, the lens barrel 114′ is dropped directly onto theimager 140 as shown in FIG. 6. The lens barrel 114′ includes a specialdesigned mechanical feature such as rebate 202 (see detail view of FIG.6A) so that, while the lens barrel 114′ is dropped to onto the imager140, the rebate 202 guides the lens 112′ to have proper horizontalalignment such that the lens optical axis is in line with the center ofthe imager sensing area (the alignment of optics axis to the center ofthe imager can also be achieved by digital shifting of image sensingwindow on imager. This digital center shifting feature can be found insome imagers, such as, for example, an Aptina MT9V126 CMOS imager).

As shown in FIG. 6, the lens 112′ can be secured by applying adhesive204 (such as UV-cured adhesive) around the interface of the lens barrel114′ with the imager 140 and PCB 138, thus fixing the lens focusposition. In a variant 200′ shown in FIG. 7, an alternative way to fixthe lens 112′ to the imager 140 is to include metal insert pins 206 inthe lens barrel 114′. The metal insert 206 is then soldered to the PCB138 during PCB reflow process to fix the lens 112′ to the PCB 138.

As shown in FIG. 8, the distance from the lens principal plane LPP tothe lens seating surface H1 (which is defined by a cover glass 158 thatis spaced apart from imaging sensor surface 160), and the distance H2between the imaging sensor surface 160 to the top surface of cover glass158 need to satisfy the relation H1+H2=F+ΔF, where F is the effectivefocal length of the lens, and ΔF is the focus tolerance range.

ΔF multiplied by two (ΔF*2) is also called depth of focus, which canrange from a few micrometers to hundreds of micrometers. For a typicalautomotive camera, the depth of focus is about 40 to 70 micrometers. H1and H2 are the two sources that contribute to the variation of focus.The lens barrel 114′ may be designed to have a tightly controlled lengthtolerance. The barrel length can be designed such that when it isdropped on the imager cover glass 158, the lens is focused right to theimager sensing surface 160 nominally. The imager 140 can also bedesigned such that the distance H2 between the sensing surface 160 andthe top cover glass surface of the imager has a tight tolerance.However, the lenses and imagers manufactured will always have variationsfrom their designed nominal values. The variation of H1 and H2 can stackup and drive the lens imager pair out of focus.

To control the focus tolerance and increase manufacturing yield, one ormore of the following methods can be employed:

First, use optical technology such as wavefront coding as promoted byOmniVision. The technology uses specially designed lens elements andimage processing algorithm to increase the depth of focus (ΔF) of thelens. The wider lens depth of focus allows more tolerate of focusposition variation. The manufacturing yield and product focus qualitycan be maintained high.

Second, use a laser or other means to cut or ablate extra lens barrelmaterial in the bottom of the lens barrel 114′ so that the correct lensbarrel length can be altered to achieve good focus. A pre-laser ablationfocus measurement is performed to determine how much barrel material toablate. To address the case that the lens being too short, one candesign the lens barrel so that it is always in the longer side.

Third, bin and match lens 112′ and imager 140 to achieve good drop-onfocus. The idea is to measure and sort lenses and imagers. Bin thelenses and imagers to matching groups. For example, a lens group withPlus 20 to 30 micrometer too long of flange focal length is matched withan imager group with Minus 20 to 30 micrometer too short of silicon totop glass distance. The two groups will form a good focus camera.

It will thus be seen that by directly dropping the lens 112′ to theimage sensor 140, it is possible to avoid a time-consuming assembly stepin the camera manufacturing process which requires actively searchingfor best focus position. It results in a reduced cycling time andincreased production efficiency, and avoids the use of a very expensivemulti-axis focus machine.

Embodiment 4 Lens Focus by PCB Mounting and Focusing Screws

FIG. 9 shows another embodiment 300 of a vehicular camera where a camerafront housing 330 includes a mechanical guidance feature such as wall302 for guiding the lens 112 to proper horizontal alignment with theimager 140 so that the lens optical axis is in line with the center ofthe imager sensing surface. In this embodiment, the PCB 138 with imager140 is attached to the front housing 330 by screws 304 but alsoutilizing compressive gaskets, wave washers or lock washers 306 heldbetween the PCB 138 and body of the front housing 330. The focusingbetween the lens 112 to imager 140 is accomplished by turning thesescrews 304 and actively monitoring camera output.

The alignment of the lens optical axis and imager center can be achievedby digitally shifting the image window on the imager.

Referring additionally to FIG. 10, the attachment of the camera backhousing 132 to the front housing 330 (not drawn in this drawing) can beachieved by laser or ultrasonic welding, glue, press fitting, screwtogether or other means.

The camera front housing in this embodiment may also employ anintegrated lens barrel as discussed above with respect to embodiment110.

Embodiment 5 Lens Focused by Positioning of Camera Front and BackHousings

FIG. 11 shows another embodiment 400 of a vehicular camera in which theintegrated lens barrel and camera upper housing piece 150 of embodiment110 is attached to the camera back housing 132 by UV cured glue 402. Theglue is applied before focus. An active focus and alignment (utilizing amulti-axis focusing machine) is performed to reach optimum lens focusand optical axis alignment to the imager center. While holding theintegrated lens barrel and camera front housing piece 150 in theposition achieving the best focus and alignment, a robot applies UVillumination to the adhesive to cure it and fix the position of the lens112′ and seal the camera. In this embodiment, the PCB 138 is mounted toback housing by screws 134, glue between PCB and back housing or othermeans.

In a variant 400′ shown in FIG. 12, the UV cured adhesive 402′ alsoreplaces the screws 134 used to mount the PCB 138 to the housing. Theadhesive 402′ thus attaches the PCB 132 to the back housing 138, fixesthe integrated piece 150 to the back housing 132, and seals the camera.

In another variant 400″ shown in FIG. 13, the imager PCB is focused andaligned and then fixed to the lens barrel and camera front housing piece150 by UV cured adhesive 402″ applied on and between the PCB 138 andstandoff parts 404″ of the integrated piece 150. During the focusassembly process, the imager PCB 138 is grabbed and moved in x, y and zdirection(s), and optionally in two rotational directions, to achieveoptimum focus and alignment. While the imager PCB 138 is being held inthe position, UV illumination is applied to cure the adhesive 402″.

Embodiment 6 Direct Attachment of Lens and Imager by Adhesive

FIG. 14 shows another embodiment 500 of a vehicular camera in whichtransparent UV-curable adhesive 502 is applied directly between lens 112and imager 140 and/or PCB 138. The adhesive 502 is provided as arelatively large blob to bonds the lens 112 to the imager 140 and/or thePCB 138. The focus and alignment of the lens 112 is performed before UVlight cures the adhesive. The adhesive preferably encapsulates theimager 140 and acts a protective shield for it.

In a preferred method of assembly, adhesive is applied on and around theimager in a controlled amount. A robot, such as a five-axis robot or thelike (with motions in the x, y and z axes or directions and at least twoorthogonal rotations and preferably a six-axis robot with translationalmotions in the x, y and z orthogonal axes and three orthogonalrotations), also grips and dips the lens into a batch of adhesive. Therobot then focuses and aligns the lens to the imager (such as viaadjustment of the lens and/or imager relative to one another via sixdegrees of freedom), whereupon UV light is applied to cure the adhesive.The robot then releases the lens.

This embodiment simplifies the lens barrel design and reduces the lenssize. This embodiment can also be more advantageous than embodimentsthat utilize a threaded lens, which can be slow to focus or difficult tohold, or a press-fit lens, which provides only coarse movement and thuscan be difficult to control. Thus, a more accurate alignment can beobtained.

In all of the foregoing embodiments its also desired to reduce the costof the lens itself. This can be accomplished in one or more of thefollowing ways.

For example, plastic may be used for the lens barrel 114 and retainercap 116. The barrel and cap are preferably made by injection molding ofplastic material like PPS. This material is dense, nonporous, rigid andhas ultra low hygroscopic characteristics and thus it meets the specialenvironmental and durability requirements for a rear view camera lens.

Optionally, for example, the lens 112′ may be formed to incorporate onlyone glass element as the outer-most element 120 a (FIG. 4) of the lens,and utilize two or three plastics lens (made by injection molding) forthe inner optical elements. An alternative configuration may include twoglass elements and one or two plastic lenses. Minimizing the number ofglass elements reduces cost of the optical components.

In addition, cost savings may be realized by eliminating the lens IRcutoff filter 126 which is conventionally provided as a glass plate.Instead, the IR cutoff filter can be moved to the imager cover glass 120a. One added benefit of eliminating the IR cutoff filter in the lens isthat it reduces or eliminate light multi-reflection between the flat IRcutoff filter and imager cover glass 120 a. This multi-reflection cancause lens flare and ghost images.

Optionally, for example, lens cost may also or otherwise be reduced bylowering the lens resolution. The lens resolution can be reduced to alevel that fits the application requirement of the camera. Moreparticularly, the human eye resolution perception can be represented bya contrast sensitivity function (CSF) as shown in FIG. 15. The CSF peakswithin a range of 1 to eight cycles per degree, where a cycle is definedas a one transition from black to white (or vice versa), which may bereferred to in the literature as a “line pair”. Thus, a requiredresolution can be determined from the display size, the distance betweenthe observer and the display, the selected CSF, and the size of theimager sensing surface.

For example, consider a 7-inch diagonal display (with a 16×9) aspectratio. It has a horizontal dimension of 155 mm. Assume the distancebetween the observer and the display is 600 mm, which is the averagedistance between a driver's eyes and a display in the vehicle centerconsole. Select a CSF of 7 cycles per degree, which is a reasonablecompromise between machine vision and human vision requirements. Andassume that the imager has a horizontal sensing width of 3.58 mm. Oneangular degree represents a width of 10.5 mm at distance of 600 mm. Thedisplay resolution required is 0.67 line pairs/mm. The required cameraresolution is thus 28.9 line pairs per mm. Thus, a camera can produce asufficient resolution is its lens yields a camera level modulationtransfer function of 28.9 line pairs per mm.

Other examples of sufficient camera resolutions are provided in thechart below:

Display diagonal size 8 7 6 3.5 2.5 (inch) Aspect Ratio 16 × 9 16 × 9 16× 9 4 × 3 4 × 3 Horizontal Dimension 177 155 133 71.1 50.8 (mm) Eye toDisplay Distance 600 600 600 500 500 (mm) mm per 1 degree at 10.5 10.510.5 8.7 8.7 Display At display resolution 0.668 0.668 0.668 0.802 0.802(lp/mm) Required camera 33.0 28.9 24.8 15.9 11.4 resolution (lp/mm)

Thus, lens resolution can be reduced to the limits dictated by the CSFin order to reduce cost. Prior art lenses may have too high resolutionfor human visual perception, and high resolution lenses can adverselycause a negative consequence called the “Moire Effect”. Some of priorart camera designs utilized an optical low pass filter to lower theimage sharpness of the lens to eliminate the “Moire Effect”. The opticallow pass filter adds cost to camera along with the higher cost highresolution lens.

Optionally, for example, lens cost may also or otherwise be reduced bynot optically addressing any chromatic aberration in lens. Lenschromatic aberration can cause the resultant image to have color fringesat the edges of objects, as well as lower image resolution. Lenschromatic aberration can typically be fixed or mitigated by a pair ofglass lens cemented together, the so-called achromat pair. However, fora low cost lens solution, the chromatic aberration is not fixed in thelens, rather, the imager system-on-chip (SOC) or an adjunct digitalprocessor applies digital correction to correct the chromaticaberration. The chromatic aberration typically has fixed amount ofspatial separation among different colors at a specific off-axis angle,as shown in the lateral color diagram example of FIG. 16.

The basic principle of digital correction of chromatic aberration is asfollows.

Every pixel of an imager has individual values of red, green and bluecolors. By shifting one pixel colors to one or more other pixels, andrepeat the process to the whole imager, it is possible to correct orreduce the effect of lens chromatic aberration. Based on the lateralcolor separation of the lens, like the example graph shown in FIG. 16,the separation of the color as a function of the distance from thecenter of the imager is known. For each imager pixel, it is possible tocalculate the distance needed to shift every individual colors of thepixel. The shift happens in a radial direction because of the lens'symmetry to its axis. In each pixel, new position coordinates of eachcolor is re-calculated. Then this color value will be sent to the newpixel whose coordinates were calculated. The other two colors of thispixel are also calculated and sent to new pixels.

This shifting or redistribution of the pixel colors can be performed inSystem-On-Chip (SOC) part of imager, or a separate processor after theimager. The processor can be a microprocessor, a DSP, or a FPGA or otherdigital devices. Adding some gates or logical units to an existingdigital processing unit most likely is less expensive than addingachromat glass elements in lenses. The lens chromatic aberration istypically symmetric over the optical axis, which lowers the complexityof digital chromatic aberration in the SOC or processor.

Lens manufacturing variation may cause the chromatic aberration to notbe totally cylindrically symmetric. The spectral response of everyimager pixel may thus have variations. To correct the negative effect todigital chromatic aberration caused by these two variations, one canapply calibration procedures. During a calibration procedure, a specialtarget, an image acquisition and image processing algorithms are used tocalculate lateral color separation at every pixel. Then the pixelrelated lateral color values are used in digital chromatic aberrationcorrection process described above.

Use of Robot to Adhere PCB to Lens Assembly

Referring now to FIGS. 17 and 18, a vehicular camera 610 includes a lensassembly 614 and a circuit element 620 (such as a printed circuit boardor the like) and a housing portion 612. Circuit element 620 comprises animaging sensor, such as a VGA or megapixel imaging array, preferably aCMOS imaging array, such as an imaging array utilizing aspects of theimaging arrays described in U.S. Pat. Nos. 6,396,397; 5,877,897;5,796,094; 5,670,935; and/or 5,550,677, which are hereby incorporatedherein by reference in their entireties. Lens assembly 614 comprises abase portion 614 a and a barrel portion 614 b with lens optics(typically a plurality of individual glass and/or plastic lens elementsthat provide a wide angle and preferably a distortion corrected wideangle field of view for the vehicular camera) disposed therein. The lensassembly 614 may be provided as a pre-assembled element or construction.The circuit element 612 comprises a substrate 612 a (such as asemiconductor substrate or a printed circuit board substrate or thelike) with circuitry 612 b established thereat or thereon, including animaging array and associated circuitry. The circuit element 612 isadhered to the base portion 614 a of the lens assembly 614 via curing ofa plurality of adhesive beads or bead segments or dots 630 dispensed ator around or between the base portion 614 a and circuit element 612, asdiscussed below. A rear housing or housing portion 632 is attached tothe base portion 614 a to substantially encase and seal (from the likesof water intrusion and/or intrusion by contaminants such as dirt, debrisand the like) the circuit element 612 within and between housing portion632 and lens assembly 614, as also discussed below.

The adhesive dots or beads or bead segments 630 may comprise anysuitable adhesive, preferably an adhesive that may be initiallypartially cured via exposure to ultraviolet (UV) light for a shortperiod of time (and optionally partially cured via a sequence of UVlight exposure curing processes), and then later fully cured to itsfinal cure state via a secondary curing process or a sequence ofsecondary curing processes, such as via exposure to elevated temperaturefor a period of time, such as an adhesive of the types discussed above.Although shown and described as having the adhesive beads or beadsegments or dots dispensed at the fixtured base portion of the lensassembly, clearly, the adhesive beads or bead segments or dots mayoptionally be dispensed at the circuit element and/or the circuitelement may be fixtured and the lens assembly may be moved or placed atthe fixtured circuit element by a robot (such as a six axis robot or thelike, such as discussed above), while remaining within the spirit andscope of the present invention.

The assembly process of the present invention includes placing the lensassembly 614 in a fixture and dispensing the adhesive dots 630 around aportion of the base portion 614 a of the lens assembly. The adhesivedots or beads or bead segments are preferably dispensed at an insidesurface of the base portion of the lens assembly (a surface that will bewithin the camera when the camera is fully assembled), and thus theadhesive need not be established or dispensed as a continuous orunbroken bead so as to create or establish a seal to the outsideenvironment, and thus less adhesive can be used to adhere the circuitelement (and imaging array) relative to the lens assembly (as comparedto the embodiments similar to those discussed above where a continuousbead of adhesive is dispensed about an interface between the lens andthe housing portion).

A robot or robotic device (such as a six axis robot as discussed abovethat is operable to grab and move objects in up to six axes of motion,such as three generally orthogonal translational axes (in the x, y and zdirections) and up to three generally orthogonal rotational axes (apitch axis, a yaw axis and a roll axis)) or the like may pick up thecircuit element 620 and position the circuit element at the base portion614 a and place the circuit element on or at the adhesive dots 630. Sucha robot is operable to grab the imager circuit element and move theimager circuit element in up to six axes of motion, such as along threegenerally orthogonal translational axes, such as along either or both ofthe x and y axes or directions (the generally orthogonal axes that aregenerally parallel to the plane of the base portion of the lens assemblyand generally orthogonal to the optical axis of the lens or lensassembly) and along the z-axis or direction (the axis that is generallyorthogonal to the plane of the base portion of the lens assembly andgenerally along the optical axis of the lens or lens assembly). Inaddition to the translational movement capabilities of the robot, therobot is also operable to move or rotate or pivot the circuit elementand the grasping or holding portion or head of the robot about threegenerally orthogonal rotational axes, so as to provide a pitch rotationor movement (rotation of the held circuit element about one of thegenerally orthogonal axes that are generally parallel to the plane ofthe base portion of the lens assembly and generally orthogonal to theoptical axis of the lens or lens assembly), a yaw rotation or movement(rotation of the held circuit element about the other of the generallyorthogonal axes that are generally parallel to the plane of the baseportion of the lens assembly and generally orthogonal to the opticalaxis of the lens or lens assembly) and a roll rotation or movement(rotation of the held circuit element about the axis generallyorthogonal to the plane of the base portion of the lens assembly andgenerally along the optical axis of the lens or lens assembly).

When the robot has positioned the circuit element on or at the adhesivedots 630 at the base portion of the lens assembly (such as with thecircuit element pressed partially against or contacting the adhesivebeads or dots), the assembly process or system sets or positions oradjusts the circuit element relative to the base portion (with theadhesive dots being flexible or resilient in its uncured state to allowfor adjustment or movement of the circuit element when the circuitelement is engaged with or set at or on the adhesive dots) to preciselyset or align the optic elements with the imaging array of the circuitelement (such as by aligning the optical elements with the imaging arrayin x, y and z axes and pitch, yaw and roll or rotation). This ispreferably done automatically by powering up the camera 610 andcomparing an actual image captured to that of a standard calibrationimage. The five or six axis robot thus manipulates or moves the grippedcircuit element 620 in three dimensional space (relative to the fixturedlens assembly) and with multiple axes of freedom until the automaticcalibration determines that the focus and/or other alignment of the lensrelative to the imaging array is correct or within a thresholdtolerance.

When it is determined that the imaging array and optic elements areprecisely aligned so that the optics properly focus images onto theimaging plane of the imaging array, the adhesive dots may be initiallyor partially cured via relatively brief exposure to UV light (such asfor a duration of about seven seconds or thereabouts) to set the imagingarray relative to the optic elements at the desired or appropriatealignment. The now joined circuit element and lens assembly may thenindex or move to a further partial curing stage that is a longer timeduration than the initial brief exposure. The robot then can proceed topick up another circuit element for positioning at or relative toanother lens assembly, and thus, the utilization of expensive capitalitems, such as the robot itself, is enhanced or optimized. For example,the first UV cure duration or UV exposure may be less than about 10seconds in duration, preferably less than about 7 seconds and typicallygreater than about 3 seconds, such as in a range of about 5 to 7 secondsor thereabouts. The further or second UV cure duration or UV exposuremay be less than about 35 seconds, preferably less than about 20 secondsand greater than about 10 seconds, such as in a range of about 15 to 20seconds or thereabouts. Thus, the robot is utilized to join the circuitelement at the lens assembly and to align the lens optics with theimaging array and hold them in alignment during a relatively brief UVexposure, after which the joined circuit element and lens assembly maybe moved or conveyed from the robotic station to a second or further UVexposure to further cure the adhesive (and during which time the robotmay be used to assemble and align another circuit/lens subassembly) sothat the parts are substantially joined for movement to a secondarycuring station remote from the robotic station.

After the adhesive dots have been initially or partially cured(preferably after an initial shorter duration UV exposure immediatelyfollowed by another longer duration UV exposure), the lens assembly andcircuit board construction (now substantially joined via the partiallycured adhesive) can be moved to a secondary curing station (remote fromor separate from the robotic station at which the circuit board isadhered to the lens assembly) to fully cure the adhesive dots to theirfinal or fully cured state (such as via thermal curing). For example,the secondary curing station (or final curing station) may comprise anoven or heat chamber, where the lens assembly and circuit boardconstruction may be heated to an elevated temperature (such as, forexample, about 95 degrees C. or thereabouts) for a sufficient amount oftime (such as, for example, about five minutes or thereabouts) to fullycure the adhesive (and optionally providing a cool down time followingthe heating of the adhesive and lens assembly and circuit boardconstruction). Plainly, the oven can accommodate multiple cameras or mayhave a conveyor or lehr that moves the cameras through the oven so thateach camera is in the oven and being heated by the oven for thepredetermined or selected period of time.

In the illustrated embodiment of FIGS. 17 and 18, the lens assembly 614is provided as a pre-assembled construction, with the lens barrel andbase portion unitarily formed or pre-assembled with the lens optics inthe barrel portion. Thus, the unibody lens assembly may be fixtured orfixedly supported for attachment or adhering of the circuit board to thebase portion of the lens assembly. Optionally, and as shown in FIG. 19,a lens assembly 614′ may comprise a separate base portion 614 a′ andbarrel portion 614 b′, where an initial step of the assembly process maycomprise adhering the barrel portion to the base portion to constructthe lens assembly. The other components of the camera 610′ shown in FIG.19 may be similar to the components of camera 610 of FIG. 18, such thata detailed discussion of the common or similar components need not berepeated herein.

After the circuit element 612 is adhered to the lens assembly 614 andthe adhesive is cured, the housing portion 632 is attached to and sealedto the base portion 614 a of lens assembly 614, such as via laserwelding or the like. For example, the housing portion may besealed/attached at the base portion by utilizing aspects of the cameraassemblies described in U.S. Pat. No. 7,965,336, and/or U.S. patentapplication Ser. No. 12/091,359, filed Apr. 24, 2008 and published Oct.1, 2009 as U.S. Publication No. US-2009-0244361, which are herebyincorporated herein by reference in their entireties. The housingportion and base portion of the lens assembly thus encase the circuitboard or element therein or therebetween to provide a water tight orsubstantially water impervious housing or encasement for the circuitelement and imaging array and circuitry. In the illustrated embodiment,the circuit element includes electrically conductive terminals or leads612 c that are electrically connected to circuitry 612 b and thatprotrude from the circuit substrate or board 612 a and are received in aconnector portion 632 a of housing portion 632 when the housing 632 isattached to the base portion 614 a of lens assembly 614. The terminals612 c thus are received in an electrical connector to provide amulti-pin connector for electrically connecting the camera 610 to awiring harness of a vehicle when the camera is installed or mounted atthe vehicle.

Thus, the present invention provides an assembly process for assemblinga vehicular camera that adheres a circuit board to a base portion of alens assembly to align and affix the imaging array of the circuit boardrelative to the lens optics of the lens assembly. With reference to FIG.20, the process 650 may include loading of an integrated lens holder orlens assembly into a holding fixture at 652. The fixture may includelocating features or elements that allow the lens assembly or lensholder to be properly positioned for each camera and to be biased to thecomponent's pre-determined datums. Optionally, pallet tracking software(such as RFID tracking software or the like) may be used to track eachassembly pallet as it transfers from station to station during theprocess. The lens assembly may be picked and placed at the fixture via arobotic device or suitable automated or manual process, such as via athree-axis module. The base portion may be plasma-treated and theadhesive dots or beads or bead segments may be dispensed at the baseportion of the lens assembly at 654. The plasma-treating process may beaccomplished via any suitable means. The adhesive beads or dots may bedispensed via any suitable dispenser, such as via a servo dispenser heador the like, and the dispensing may be monitored by a vision system(such as a Cognex micro 1050 vision camera or the like) to verify thatthe appropriate amount of adhesive was dispensed at the properlocations. The servo dispense head (such as a Viscotech dispense head orthe like) may be mounted to a robot.

The circuit element may be automatically picked from a tray/stacker andplaced at or on the dispensed adhesive dots at 656, whereby the systemmay perform the x, y and z (and pitch, yaw and roll or rotation) focusof the lens relative to the imaging array. A robot may be used to placethe circuit board at the adhesive dots and adjust the circuit elementand imaging array to achieve the desired or appropriate focus. After thefocus level is achieved, the system may flash UV cure the adhesive dots,such as via a flash UV cure system, such as a Lesco, Super Spot “Max”system or the like (for a brief UV exposure duration, such as less thanabout 10 seconds or thereabouts), and the system may subsequentlyfurther UV cure the adhesive via a second or subsequent or further UVcure system (for a longer UV exposure duration, such as greater thanabout 10 seconds and less than about 35 seconds or thereabouts). Thefurther UV curing station may be along the same conveyor line andadjacent to the robotic station so that the lens and circuit elementconstruction is not substantially moved until after it has undergone thefurther UV cure/exposure. The lens and circuit element construction(with the lens assembly and circuit element joined by the partiallycured adhesive) is moved to a secondary cure system or station at 658(such as a thermal curing station or the like that may be remote fromthe robotic station and UV curing station) where the adhesive is furthercured to a substantially cured state. The housing portion may beattached to the base portion to encase and/or seal the circuit elementand imaging array therein and/or the camera subassembly or constructionmay be offloaded at 660. Optionally, and with reference to FIG. 21,other steps or processes may be included in the camera constructionprocess, while remaining within the spirit and scope of the presentinvention. Optionally, and with reference to FIG. 22, other steps orprocesses may be included in the camera construction process where thelens assembly is provided as a two piece construction, such as theconstruction shown in FIG. 19, while remaining within the spirit andscope of the present invention.

The system or method of the present invention moves the circuit boardand imaging array to the optical center of the lens and thus results inpositive x-axis and y-axis positioning for vehicle packaging. The frontend pallet or fixture design may continue to datum off “A” surface butwill not require electrical connection, and the circuitry of the circuitelement or PCB may be electrically engaged at the align and focus stageor station. The system thus may reduce false failures that may occur dueto pallet connections. Also, there is no requirement of articulation ofthe lens for the plasma treat process. The system also provides for areduction of unscheduled down time for gripper repair and replacement.

The six axis robot and alignment system of the present invention thusmay properly position and align and adhere the lens or optics relativeto the imager and may properly position and align and adhere the imagerrelative to the camera body. Optionally, the lens and camera bodyportion may be provided as a pre-assembled unit (such as shown in FIGS.17 and 18) or may be assembled together before attachment of the imagerand circuit element thereat, whereby the imager and circuit element orcircuit board are placed at and adhered at the camera body portion via asix axis robot such as discussed above. For example, the imager andcircuit element or printed circuit board may be picked up by the robotand positioned and aligned at the camera body portion to properly orientthe imager relative to the camera body. For example, the circuit elementmay be moved via the robot along all three translational axes (x, y andz axes) to position the circuit element (and imager established thereat)generally at the camera body portion, and the robot may tilt or pivot orrotate the circuit element about the x and y axes and may pivot orrotate or roll the circuit element about the z-axis to properly alignand orient the imager at the lens optics and at the camera body portion.When the circuit element is at the appropriate location and alignmentand orientation, the circuit element is adhered to the camera bodyportion (such as via the two stage curing of the adhesive as discussedabove).

The ability of the robot to adjust the circuit element and imager aboutthe z-axis ensures proper alignment of the imager relative to the camerabody portion, such that, when the camera body is fully assembled andsealed (i.e., after the back portion of the camera body is attached andsealed at the front camera body portion and lens assembly) and mountedat a vehicle (via use of datums at the camera body, such as at the frontcamera body portion, that align with or engage datums at the vehiclemounting structure to precisely position the camera body at thevehicle), the imager is properly and precisely oriented not onlyrelative to the camera body but also relative to the vehicle at whichthe camera is mounted. Thus, the six axis robot of the present inventionprecisely aligns and orients the imager relative to the lens optics andrelative to the camera body, so that images captured by the camera whenthe camera is mounted on a vehicle are properly focused and properlyoriented relative to the vehicle and relative to the horizon and vehiclebumper (such as for a rearward facing camera at a rear portion of thevehicle).

The process of placing and gluing the circuit element at the lensassembly and/or camera body or body portion utilizes an adhesive thatallows for a dual curing process or dual stage cure, where an initialcure may be quickly achieved via UV exposure and a final cure may belater achieved via a low temperature thermal cure. For example, the typeor form of adhesive is referred to as an epoxy-amine adhesive. It isunique because it has a dual cure mechanism that allows it to be quicklycured via UV light exposure and then further or completely cured to avery high strength via heat exposure or thermal cure. The required curetemperature for this adhesive is relatively low (such as in the range ofabout 85 degrees C. to about 95 degrees C.) as compared to other knownadhesives or similar chemistries. This adhesive type is genericallyreferred to as a Dual Bond adhesive commercially available from DeloIndustrial Adhesives of Windach, Germany. The exact mix used in theabove described embodiments is Delos AD VE 43812, but clearly otheradhesives having similar properties as described above may be utilizedwhile remaining within the spirit and scope of the present invention. Akey advantage for such an adhesive (having a quick UV cure step with afollow-up low temperature thermal cure step) is that it is ideal forhigh production or high volume camera assembly processes. The quick UVcure allows the system to quickly shuttle fixtured components out ofhigh cost focus and alignment stations to lower cost thermal curestations, such that the time spent by the assembly at the high coststations is minimized.

Thus, the present invention provides an enhanced assembly process forassembling or manufacturing vehicular cameras or camera modules. The twostage curing process allows the system to quickly partially cure theadhesive that holds the circuit element and imaging array relative tothe lens optics so that the circuit and lens sub-assembly may be movedfrom the robot station to a later or subsequent secondary curingstation, while the robot may quickly be ready to pick and place andadhere and align another circuit element and imaging array with anotherfixtured lens assembly at the same time that the first circuit and lenssub-assembly is being further cured at a different station. The presentinvention thus provides for reduced time usage of the robotic device sothat it can be used on subsequent cameras while the earlier cameras arefully cured at a separate curing station. The system may comprise asecondary UV curing station at or near the robotic station andoptionally along a conveyor line that moves or conveys the parts from afixturing station to the robotic station and initial UV curing station(where the components are joined and aligned and the adhesive is brieflyexposed to UV light) to the further UV curing station (where theadhesive is again exposed to UV light, but for a longer period of time)and to an unloading or offloading station. Optionally, a secondarycuring station may be provided to thermally cure the adhesive to itssubstantially final cure state (such as via an oven or the like), oroptionally, the secondary curing station may comprise another type ofcuring station, while remaining within the spirit and scope of thepresent invention (with the secondary curing station optionally beingremote from the robotic station and UV curing stations).

While the above describes particular embodiment(s) of the invention, itwill be appreciated that modifications and variations may be made to thedetailed embodiment(s) described herein without departing from thespirit of the invention.

The invention claimed is:
 1. A method of assembling a vehicular camera, said method comprising: providing a lens assembly comprising a base portion, a lens barrel and a plurality of optical elements in said lens barrel; providing a circuit element comprising a circuit board and an imaging array established at said circuit board; dispensing at least one adhesive bead at one of (i) said base portion of said lens assembly and (ii) said circuit element; placing said circuit element at said base portion of said lens assembly with said at least one adhesive bead between said circuit element and said base portion; aligning said lens assembly with said imaging array when said circuit element is placed at said base portion and in contact with said at least one adhesive bead; wherein aligning said lens assembly with said imaging array comprises aligning said lens assembly with said imaging array via a multi-axis robotic device; curing said at least one adhesive bead to a first cure level via exposure of said at least one adhesive bead to ultraviolet light; moving said lens assembly and said circuit element to a second curing stage and curing said at least one adhesive bead to a second cure level via heating said at least one adhesive bead to an elevated temperature for at least a selected period of time; and attaching a housing portion to said base portion of said lens assembly to encase said circuit element and substantially sealing said housing portion and said base portion together.
 2. The method of claim 1, wherein dispensing at least one adhesive bead at said base portion comprises dispensing at least four spaced apart adhesive dots at said base portion of said lens assembly.
 3. The method of claim 1, wherein aligning said lens assembly with said imaging array comprises aligning said lens assembly with said imaging array via (i) translationally moving one of said imaging array and said lens assembly relative to the other of said imaging array and said lens assembly along x, y and z axes and (ii) rotationally moving one of said imaging array and said lens assembly relative to the other of said imaging array and said lens assembly about pitch, yaw and roll axes.
 4. The method of claim 3, wherein providing a lens assembly comprises providing a lens assembly that is part of a camera body portion, and wherein aligning said lens assembly with said imaging array comprises positioning and aligning said circuit element at said camera body portion via said multi-axis robotic device.
 5. The method of claim 1, wherein curing said at least one adhesive bead to a first cure level occurs after aligning said lens assembly with said imaging array to bring said optical elements of said lens assembly in focus and optically center-aligned with said imaging array.
 6. The method of claim 1, wherein curing said at least one adhesive bead to a first cure level comprises curing said at least one adhesive bead to a first cure level via exposure of said at least one adhesive bead to ultraviolet light for less than about ten seconds.
 7. The method of claim 6, further comprising further curing said at least one adhesive bead to a further cure level via a further exposure of said at least one adhesive bead to ultraviolet light.
 8. The method of claim 7, wherein further curing said at least one adhesive bead to a further cure level comprises further curing said at least one adhesive bead to a further cure level via further exposure of said at least one adhesive bead to ultraviolet light for a period of time that is less than about twenty seconds and greater than about ten seconds.
 9. The method of claim 6, wherein moving said lens assembly and said circuit element to a second curing stage comprises moving said lens assembly and said circuit element to an oven.
 10. The method of claim 9, wherein curing said at least one adhesive bead to a second cure level comprises curing said at least one adhesive bead to a second cure level via heating said at least one adhesive bead in said oven to an elevated temperature of at least about 85 degrees C. for at least about five minutes.
 11. The method of claim 10, wherein said at least one adhesive bead comprises an epoxy-amine adhesive.
 12. The method of claim 1, wherein attaching a housing portion to said base portion of said lens assembly comprises laser welding a housing portion to said base portion of said lens assembly.
 13. The method of claim 1, wherein said housing portion comprises an electrical connector configured to electrically connect to a wiring harness of a vehicle when said camera is mounted at the vehicle.
 14. The method of claim 13, wherein said electrical connector is electrically connected to circuitry of said circuit element when said housing portion is attached to said base portion.
 15. A method of assembling a vehicular camera, said method comprising: providing a lens assembly comprising a base portion, a lens barrel and a plurality of optical elements in said lens barrel, wherein said base portion comprises part of a camera body portion of said vehicular camera; providing a circuit element comprising a circuit board and an imaging array established at said circuit board; dispensing at least one adhesive bead at one of (i) said base portion of said lens assembly and (ii) said circuit element; providing a multi-axis robotic device that is operable to (i) translationally move a grasping portion of said robotic device along an x-axis, a y-axis and a z-axis and (ii) rotationally move said grasping portion about two orthogonal axes; placing said circuit element at said base portion of said lens assembly via said robotic device so that said at least one adhesive bead is between said circuit element and said base portion; aligning said lens assembly with said imaging array and aligning said circuit element with said camera body portion via said robotic device when said circuit element is placed at said base portion and in contact with said at least one adhesive bead; wherein aligning said lens assembly with said imaging array comprises aligning said lens assembly with said imaging array and aligning said circuit element with said camera body portion via (i) translationally moving said circuit element relative to said lens assembly along x, y and z axes and (ii) rotationally moving said circuit element relative to said lens assembly about two orthogonal axes; when said imaging array and said lens assembly are aligned, at least partially curing said at least one adhesive bead; and attaching a housing portion at said base portion of said lens assembly to encase said circuit element and substantially sealing said housing portion and said base portion together.
 16. The method of claim 15, wherein at least partially curing said at least one adhesive bead occurs after aligning said lens assembly with said imaging array to bring said optical elements of said lens assembly in focus and optically center-aligned with said imaging array and after aligning said circuit element with said base portion of said lens assembly.
 17. The method of claim 15, wherein aligning said lens assembly with said imaging array comprises aligning said lens assembly with said imaging array via (i) translationally moving said circuit element relative to said lens assembly along x, y and z axes and (ii) rotationally moving said circuit element relative to said lens assembly about pitch, yaw and roll axes.
 18. The method of claim 15, wherein dispensing at least one adhesive bead at said base portion comprises dispensing at least four spaced apart adhesive dots at said base portion of said lens assembly.
 19. The method of claim 15, wherein at least partially curing said at least one adhesive bead comprises curing said at least one adhesive bead to a first cure level via exposure of said at least one adhesive bead to ultraviolet light.
 20. The method of claim 19, comprising, after curing said at least one adhesive bead to said first cure level, moving said lens assembly and said circuit element to a second curing stage and curing said at least one adhesive bead to a second cure level via heating said at least one adhesive bead to an elevated temperature for at least a selected period of time.
 21. The method of claim 15, wherein attaching said housing portion to said base portion of said lens assembly comprises laser welding.
 22. The method of claim 15, wherein said housing portion comprises an electrical connector configured to electrically connect to a wiring harness of a vehicle when said camera is mounted at the vehicle, and wherein said electrical connector is electrically connected to circuitry of said circuit element when said housing portion is attached to said base portion.
 23. A method of assembling a vehicular camera, said method comprising: providing a lens assembly comprising a base portion, a lens barrel and a plurality of optical elements in said lens barrel, wherein said base portion comprises part of a camera body portion of said vehicular camera; providing a circuit element comprising a circuit board and an imaging array established at said circuit board; dispensing at least one adhesive bead at one of (i) said base portion of said lens assembly and (ii) said circuit element; and wherein dispensing at least one adhesive bead comprises dispensing at least four spaced apart adhesive dots at one of (i) said base portion of said lens assembly and (ii) said circuit element; providing a six axis robotic device that is operable to (i) translationally move a grasping portion of said robotic device along an x-axis, a y-axis and a z-axis and (ii) rotationally move said grasping portion about said x-axis, said y-axis and said z-axis; placing said circuit element at said base portion of said lens assembly via said robotic device so that said at least one adhesive bead is between said circuit element and said base portion; aligning said lens assembly with said imaging array and aligning said circuit element with said camera body portion via said robotic device when said circuit element is placed at said base portion and in contact with said at least one adhesive bead; wherein aligning said lens assembly with said imaging array comprises aligning said lens assembly with said imaging array and aligning said circuit element with said camera body portion via (i) translationally moving one of said circuit element and said lens assembly relative to the other of said circuit element and said lens assembly along x, y and z axes and (ii) rotationally moving one of said circuit element and said lens assembly relative to the other of said circuit element and said lens assembly about pitch, yaw and roll axes; at least partially curing said at least one adhesive bead after aligning said lens assembly with said imaging array to bring said optical elements of said lens assembly in focus and optically center-aligned with said imaging array; attaching a housing portion at said base portion of said lens assembly to encase said circuit element and substantially sealing said housing portion and said base portion together; and wherein said housing portion comprises an electrical connector configured to electrically connect to a wiring harness of a vehicle when said camera is mounted at the vehicle, and wherein attaching said housing portion to said base portion includes electrically connecting said electrical connector to circuitry of said circuit element. 